Receivers for radio frequency signals are known and receivers for GMSK signals are known. Such receivers are used for some equipment that is employed in Global System for Mobile communications (GSM) systems. Generally these receivers require some form of interference cancellation. One technique for interference cancellation that has been used is referred to as a linear equalizer, wherein the effects of the channel are modeled by filters that independently process a real or in phase part and an imaginary or quadrature part of the received signal. Normally a training sequence included with a GSM transmission is used by the receiver to define the two filters.
Diversity receivers operating to receive multiple copies of a signal, when properly implemented, are known to provide improved performance in fading environments. Directly applying linear equalizer techniques to each signal in a diversity receiver for a GMSK signal as defined in GSM standards is known to be sub-optimum. Given the length of the training sequence there are not enough known points to determine the number of parameters required to jointly define linear equalizers in a GMSK diversity system.